Nuclear Techniques ›› 2015, Vol. 38 ›› Issue (2): 20502-020502.doi: 10.11889/j.0253-3219.2015.hjs.38.020502


X-ray peak shape description method and branch ratio constraint applied in spectrum unfolding

WANG Siguang WEI Jiangbo ZHANG Huan   

  1. (School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China)
  • Received:2014-11-17 Revised:2014-12-09 Online:2015-02-10 Published:2015-02-02

Abstract: Background: Although counts under peaks in overlap region of multi-channel spectrum from X- and ?-rays can provide useful information, they are usually discarded because of much difficulty in being unfolded. The line-shape of X-ray peak could be asymmetric in left and right side caused by an energy-dependent detector efficiency. Purpose: To accurately fit out the shapes for the counts under the peaks, X- and ?-ray shapes should be described accurately, and all known information should be used as constraints for reliable results. Methods: With RooFit package, a method to describe the X-ray shape is proposed: take its intrinsic shape of X-ray described by a Lorentz function and multiplied by a detector efficiency function, then convoluted with a resolution function. Results: The results tested with the codes included in this paper show: the events number of input and output agrees within their statistical errors checked even with very heavily overlapped peaks unfolded with branch ratio constraint method. Conclusion: The method and the code introduced in this paper are feasible, and they can be used as an example to unfold overlap regions in X- and ?-ray multi-channel spectrum.

Key words: Spectrum unfolding, Fit, Multi-channel spectrum